The multifunctional air quality sensor AO-CO2-M/A measures the CO2 concentration in the ambient air in the range of 0-10000 ppm (NDIR), mixed gas VOC in the range of 0...100% based on the calibration gas, the temperature and optionally the relative humidity, absolute humidity, mixing ratio or the dew point temperature of the ambient air.

The transducer converts the respective measurement results for further processing into a linear output signal 0-10 V or 4-20 mA. Furthermore, the device has a potential-free changeover contact. For which measured value this output is used, can be set individually by innovative DIP switch technology. The CO2 concentration is measured by a non-dispersive infrared sensor (NDIR). There are 3 different CO2 scales (0-2000 ppm, 0-5000 ppm, 0-10000 ppm) to choose from, which can be switched as required by innovative DIP switch technology. The relative humidity and temperature is measured by a capacitive humidity sensor. There are 4 different temperature ranges (-30...+70°C, -20...+80°C, 0...+50°C, 0...+100°C) as well as 4 different humidity measurement category (% r.H., g/m³, g/kg, TP °C) to choose from, which can be switched as required by innovative DIP switch technology. The CO2 and VOC zero point adjustment in response to the current environmental conditions can be started manual on the device at any time. The multifunctional air quality sensor starts in regular intervals an automatic re-calibration procedure, whereby a long-term stable CO2 and VOC measurement is ensured.

Measurement range CO2

0-10000 ppm, scales 0-2000/5000/10000 ppm by DIP-switch selectable

Measurement range VOC

0...100% (good / bad air quality, referring to the calibration gas)

Measurement range r.H.

0...100% r.H.

Measurement range abs. humidity

0...50 g/m³, 0...80 g/m³ (calculated) selectable by DIP switch

Measurement range air fuel ratio

0...50 g/kg, 0...80 g/kg (calculated) selectable by DIP switch

Measurement range dew point

-20 up to +50°C DP, -20 up to +80°C DP, 0 up to +50°C DP (calculated) selectable by DIP switch

After switch-on of the device follows a self-test and the tempering, which takes ca. 10 minutes depending on the environmental conditions. At this time the analogue output drifts from the actual measurement value.

Automatic calibration

To ensure an excellent long-term stability, in the interval of ca. 7 days (CO2) respectively ca. 20 days (VOC) starts an automatic recalibration. Through this automatic calibration possible drifts are compensated. This feature can be disabled on the device by DIP switch.

Manual calibration

The manual calibration of the output signal to 400 ppm (CO2 zero point) respectively 1 V (VOC zero point) will be started by pushing the button on the circuit board (push ca. 5 s until LED is blinking). Before this it is to ensure a non-stop operating of min. 10 minutes on fresh air. After successful calibration the LED will be deactivated.